Note 3 — Chapter V · LIFE OF PLATO.

It was affirmed distinctly by Hermodôrus (according to the statement of Diogenes Laertius, iii. 6) that Plato was twenty-eight years old at the time of the death of Sokrates: that is, in May, 399 B.C. (Zeller, Phil. der Griech. vol. ii. p. 39, ed. 2nd.) This would place the birth of Plato in 427 B.C. Other critics refer his birth to 428 or 429: but I agree with Zeller in thinking that the deposition of Hermodôrus is more trustworthy than any other evidence before us.

Hermodôrus was a friend and disciple of Plato, and is even said to have made money by publishing Plato’s dialogues without permission (Cic., Epist. ad Attic. xiii. 21). Suidas, Ἑρμόδωρος. He was also an author: he published a treatise Περὶ Μαθημάτων (Diog. L., Proœm. 2).

See the more recent Dissertation of Zeller, De Hermodoro Ephesio et Hermodoro Platonico, Marburg, 1859, p. 19 seq. He cites two important passages (out of the commentary of Simplikius on Aristot. Physic.) referring to the work of Hermodôrus ὁ Πλάτωνος ἕταιρος — a work Περὶ Πλάτωνος, on Plato.